The present invention relates to methods and systems for the detection of specific sequences of nucleic acids or oligonucleotides, including deoxyribonucleic acids (DNA) and ribonucleic acids (RNA). It relates more particularly to a conjugated enzyme based assay system utilizing reflective and/or transmissive optical discs for detection of specific sequences of nucleic acids.
Assay systems utilizing optical discs have been described. See, for example, Virtanen, U.S. Pat. No. 6,030,581 entitled “Laboratory in a Disk”. Such systems have enormous potential in the field of medicine, for diagnostic and other clinical assays, as well as in fields such as environmental testing and the like. Nonetheless, there remains a continuing need to develop assays that are faster, more efficient, and more economical.
Commonly assigned U.S. application Ser. No. 10/035,836 discloses a bead based DNA assay developed for the optical disc platform. Although such assays are qualitatively reproducible, quantitation of bead binding through different methods showed relatively high variations.
Enzyme assays have been widely used in a microtiter plate format. Commonly assigned U.S. Provisional Application Ser. No. 60/353,017, entitled “Data Capture and Signal Processing for Colorimetric and Fluorescent Assays as Implemented on Reflective Optical Analysis Discs”, filed on Jan. 29, 2002, discloses an enzyme assay implemented in an optical bio-disc system. In this assay, the reactants are not immobilized on the disc surface, and the reporter is not localized. This format is very useful for the detection of small molecules, but is not easily adapted to macromolecules, such as antibodies and DNA.
Assays that detect the presence of specific sequences of nucleic acids have a number of applications. For example, nucleic acid detection systems are used to test for the presence of specific disease causing agents, such as viruses or bacteria, in biological samples taken from patients. Nucleic acid detection systems are also used to test water and soil samples for specific microorganisms. Indeed, nucleic acid testing can be used to identify particular strains or types of a microorganism, which may have important implications for the appropriate response or treatment. Nucleic acid testing is also helpful in monitoring agricultural products as, for example, in testing for the presence of genetically modified crop products. As is well known, nucleic acid testing has important forensic applications as well.
What is needed, therefore, is a rapid, efficient, and economical assay system for testing various samples for specific nucleic acid sequences that also provides reproducible quantitation of the target nucleic acid.